Where once the gym reigned supreme, the iOS app has snuck in to play. More and more athletically-inclined people are opting to skip the showers and grimy mats in lieu of workouts in their own homes. It's less time and less hassle, but (hopefully) produces similar results.

I've been testing a wide variety of these fitness apps for Macworld, but I wanted to highlight my personal favorite so far (and the only one I've continued to use): FitStar.

Like many other fitness apps, FitStar aims to help you improve your personal fitness and stamina with not much more than your own body weight. It uses a mix of squats, planks, bridges, twists, leg-lifts, and yoga moves to get you stronger and faster in your daily life.

Not only is FitStar beautifully-designed--a criteria many workout apps tend to gloss over--but its programs are designed with your own personal tolerances in mind. When you start up the app, it runs you through a basic fitness test and has you rate each task; from there, you get assigned badges for your prowess in certain areas. For me, that meant a "Level 8 Legs" (thanks, roller derby!), but only a "Level 2 Core" (no thanks, sitting all day).

The app then incorporates that data into creating your workout plans, varying the time and difficulty of your exercises based on your initial feedback. I may have to hold a wall sit for longer than the average FitStar user, but it knows that I can only stand so many pushups before I feel like I'm going to die.

The program routines are always slightly different and work a variety of areas, in order to help avoid boredom. FitStar also offers a range of more targeted Freestyle sessions if your program's current workout isn't catching your fancy. You can also always preview the list of moves by selecting a session, and learn the form for a particular move by tapping on it.

It's the program's routines that sold me on FitStar--they're well-put-together, achievable, and the videos are helpful without being condescending. They also range in time, giving you the option of a seven or 40 minute workout, depending on your schedule.

My only real complaint is that routines occasionally feature a pull-up bar--something I don't have in my home--and I'd like to be able to let the app know, so it can serve me up an alternate exercise in place of the pull-up.

FitStar is free to download; those users get access to a single program routine (Get Moving) and a few Freestyle sessions. Pay $5 a month or $30 for a year, and you'll get access to FitStar's entire library of programs and Freestyle sessions.